/*
 * Copyright (C) 2012 Google Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

package interactivespaces.event.simple;

/**
 * A very simple event sampler.
 * 
 * <p>
 * This will sample at a uniform rate as determined by the sample length. Every
 * sampleLength calls will trigger a sample.
 * 
 * @author Keith M. Hughes
 */
public class EventDividerSampler {

	/**
	 * How many counts before a sample is allowed.
	 */
	private int sampleLength;

	/**
	 * The current count.
	 */
	private int currentCount;

	/**
	 * Construct a new sampler.
	 * 
	 * @param initialSampleLength
	 *            the initial sample length
	 */
	public EventDividerSampler(int initialSampleLength) {
		this.sampleLength = initialSampleLength;
	}

	/**
	 * Reset the sampler.
	 */
	public synchronized void reset() {
		currentCount = 0;
	}

	/**
	 * Sample the divider.
	 * 
	 * @return {@code true} if the client should sample.
	 */
	public synchronized boolean sample() {
		boolean result = currentCount == 0;
		currentCount = (++currentCount) % sampleLength;
		return result;
	}

	/**
	 * Change the sample length.
	 * 
	 * @param sampleLength
	 *            the new sample length
	 */
	public synchronized void setSampleLength(int sampleLength) {
		this.sampleLength = sampleLength;
	}

	/**
	 * Get the current sample length.
	 * 
	 * @return the sample length
	 */
	public synchronized int getSampleLength() {
		return sampleLength;
	}
}
